This invention relates to epoxy resin compositions. It further relates to the curing of epoxy resins. In another aspect, it relates to cure retardation of epoxy resin composition for use as film-forming corrosion inhibitors.
Epoxy resins are useful materials for applications requiring a fluid substance which can harden into a tough coating or mass after application. Epoxy resins are used for such purposes as paint bases, corrosion-resistant coatings for metal surfaces, and sand consolidation compositions.
The mechanism by which a fluid epoxy resin solution hardens into a tough substance involves a chemical reaction between the epoxy resin and a curing agent such as an amine. Tht curing agent is mixed with the epoxy resin prior to application of the resin for its intended use and the curing reaction proceeds over a period of time which varies depending upon the individual resin and curing agent.
For certain commonly-used types of epoxy resin/curing agent formulations, the cure rate of the resin is so rapid that premixing and transportation of the total formulation to the desired location is not possible. This requires that mixing of the epoxy resin and the curing agent take place at the site of application, and thus increases the time and expense of application of epoxy formulation. The burden of mixing the components of the composition is particularly great if the site for application is remote from the sources of the chemicals or presents particular difficulties of transportation and physical mixing of the chemicals. Such difficulties are encountered for example, in preparing epoxy resin compositions for application to downhole metal surfaces in oil and gas wells for protection of the metal surfaces against corrosion. The oil and gas wells are often in locations remote from the source of the chemicals. The most serious problems are posed by offshore oil wells, in which preparation and application of such a corrosion-inhibiting formulation must take place under very severe environmental conditions and limitations of space, personnel and equipment. Transportation of the separate chemicals and of equipment for mixing them on site must be arranged, and additional personnel must be assigned and trained. The expense of using cured epoxy resin compositions could thus be reduced if the epoxy resin and the curing agent could be premixed amd transported to the site without significantly reducing the effectiveness of the composition for its intended purpose.
It is therefore an object of the invention to provide a curing composition for an epoxy resin.
It is a further object to provide a method for retarding the cure of an epoxy resin composition.